Beryl Bainbridge's daughter, Jojo Davies, is lifting one painting after another outside into her back garden so they can be photographed in a clear light. The paintings are by her mother. Beryl Bainbridge died of cancer on 2 July last year, but her career as a novelist seems to have a life of its own. She has recently been honoured by Booker (she was shortlisted five times for the prize) with a special award for Master Georgie (1998) and her new novel, The Girl in the Polka dot Dress, is out in June (she did not complete it, but editor Brendan King has adroitly remastered it).

All this would be remarkable enough, but the most extraordinary thing to emerge since her death is Bainbridge's other life: as a painter. It is already being said that if Bainbridge had not succeeded as a novelist, she would have made her name in paint. The canvases are resurfacing and an exhibition is in prospect.

Jojo, who looks uncannily like her mother, albeit fairer, is still in the early days of grief. She has had less than a year to try to adjust to what is, patently, an almost ungraspable loss. But the paintings are a tremendous source of comfort because – and nothing rivals paint for this – they hold the sense of her mother's continuing presence. "In her will, Mum left us one painting each," she says. Bainbridge assumed her children would not want more, but Jojo, her brother, Aaron, and their younger sister, Rudi, have given house room to all 18 of their mother's pictures.

It is not a puzzle why they have been overlooked until now; Bainbridge dismissed them herself. If anyone admired a painting, "she'd pull a face and say, 'Oh, darling, don't be silly'". Or, at best, she might admit: "That bit is quite nice." Yet she continued to feel the pull towards painting – and painters. Jojo's father, Austin Davies, was a painter and photographer and when their marriage ended, Beryl had a five-year relationship with another painter, Don McKinlay, which was an "incredibly creative time".

It may partly have been in comparison to these men that Bainbridge did not rate her own work. A pity, you might say – but Jojo's theory is that "because she wasn't competing, she had a terrific freedom". Painting was blessedly recreational and she adored making up stories on canvas (fiction in oils). Jojo recalls Captain Dalhousie's Wedding, in which a sea captain stands "stark naked except for his hat, with his horse behind him". His wife, Mrs Dalhousie, is starkers, too, with a huge posy between her legs. She was modelled on "Pauline, a neighbour down the road" – a "vast" woman (who also shouldered her way into The Bottle Factory Outing).

Bainbridge never cared particularly for contemporary art (Francis Bacon was an exception), but she had a cherished photograph of Chagall on her wall. What she enjoyed most were narrative-rich battle paintings and Victorian hospital scenes of the sick and wounded. She had no formal art training but was artistic from an early age – and, if anything, over-effective. Her illustration of a rude rhyme, discovered in her gymslip pocket, contributed to her expulsion from Merchant Taylors' Girls School in Liverpool. And when she left school it was to pursue a third talent – as an actress.

She cannot have failed to learn about painting from Austin Davies, who taught at Liverpool School of Art. "It was the late 1950s. They were such a hip couple – and there were lots of painters and musicians in Liverpool. Stuart Sutcliffe – the Beatle who died – used to babysit for us. John Lennon was at Liverpool School of Art and my father taught him." And what of Don McKinlay? How much did he, in turn, influence Bainbridge? He was a "fantastically important figure and painter". Jojo adds that she would love to see him again. When she looks at the painting Napoleon When Young, she observes that the face is Don's and the view from the window is of the Lancashire farm where they lived with him for a year, in 1968. "Their bedroom was an area with massive paintings on the go. We had no television but a huge dolls' house that we peopled with plasticine fathers, mothers, babies, sideboards and plants." Jojo loves being reminded of the farm, "because I was a child there. While we are still in this huge feeling of loss, I can look at pictures of the farm and feel we will always be there". Did her mother stay in touch with McKinlay? "Yes," says Jojo, in a voice that sounds uncertain, as though she more or less means no. "But Mum knew the time together was no longer there."

In later life, whenever Bainbridge finished a novel, she would start a painting, usually inspired by the book. It sounds a celebratory ritual, as if she were trying to marry her two talents. Was the painting a release from the writing? Jojo believes it was more about expediency. Beryl told her that she "missed" painting when writing. And so, when a completed novel created a gap, she would pick up her brushes. "She had a fantastic wicker box with all her oils and a palette knife… but she was a very messy painter."

Jojo works as a midwife and is, not surprisingly, artistic herself (she studied at Liverpool School of Art). She remembers, at 15, her mother directing her first attempts at painting. "You must start with a self-portrait," she said. Her father told her painting was a "waste of time". He had, by this stage, become "disillusioned": his first show had been successful, his second badly reviewed and he had gone into a decline. "He burnt all his paintings." Better to feel – as Beryl seems to have done – that painting was fun.

Once the paintings have been inspected, we go inside. Jojo digs out a photo of Beryl and Don on the doorstep of Albert Street, Camden Town, north London, where her mother lived for 40 years. The picture was taken by her father (after Bainbridge divorced him, Austin Davies lived for a while in the basement flat of the house). There is a loving flamboyance and mischief on their faces. "So hip and happy…" says Jojo. "It was 43 years ago."

Jojo's house in Muswell Hill is full of the amazing spoils of Albert Street: Eric the much-written-about stuffed buffalo has moved into her spacious hall. He looks slightly the worse for wear, but stunned, his balding cheek exposing straw. Jojo plans gentle surgery: a new glass eye has been purchased. And a lot of Bainbridge's religious statues have congregated in the living room: quiet saints, a thoughtful angel; Jesus is on the landing. Jojo studies another photo – Beryl holding hands with her and Rudi as little girls. They are shopping in a market. Looking at it, she exclaims fondly: "Mum looks so glamorous!" and remembers (though the picture is in black and white) "that pinky-brown lipstick!"

The photos, the wayward icons and the buffalo remind one of what a visual person Bainbridge was (and in her writing, too). It wasn't just canvases she painted. "She didn't like appliances," Jojo says. "She hated white boxes" and would paint "fridges – anything". On one occasion, she painted an entire piano (white with loops of flowers).

But in her last 10 years, creativity was harder to come by. Writing was often a torment. She was honest about this and Jojo remembers her bravely maintaining in a television interview that "the creative urge was tied up with sexuality. When you lose the sexual urge, you lose creativity". Jojo remembers her reading aloud from her published novels and asking herself: "How did I do that?" At worst, she would weep and say: "I can't bloody do this." Jojo would pass the message on to her agent, but to no avail, because: "Mum would not leave it. She could not. She did not know who she was if she wasn't writing".

Six months before her death, Bainbridge started work on a canvas to illustrate The Girl in the Polka dot Dress. She saw the heroine, Rose, as herself. She pictured her in a polka-dot dress with her hands raised, waving in a "girlish fashion". Waving goodbye, perhaps? She was not well enough to see the idea through. But it sounds, from this heroic attempt at the right image, as if it was possible that Beryl Bainbridge did not know who she was unless she was painting too.